.TH CHARON 1.SH NAMEcharon \- web browser.SH SYNOPSIS.B charon[.BI - option.RI [ value ]].RI [ url ].SH DESCRIPTION.I Charonis the Inferno graphical web browser, supporting a variety of web standards forthe download, viewing, automation and navigation of web based information and images..PPThe browser runs under the.IR wm (1)window manager, or directly on the.IR draw (3)and.IR cons (3)devices.When.I charonstarts, it checks to see if.I wmis running; if it is then.I charoncreates a new.I wmwindow for its display, otherwise it uses the whole area of the display device..PP.I Charonimplements an image cache to help reduce the overhead of revisiting pages.The image cache resides in memory for the duration of a session.The cache is managed by discarding least recently used images once the cache boundshave been reached.Currently,.I charondoes not provide a general purpose web cache; all other resources have to be reloadedwhen needed..SS Navigation.I Charonprovides navigation controls familiar to any web-surfer:back, forward, reload, home, stop and URL entry.Navigation of web-based information is by means of following HTML.IR links,this is done by clicking on them using mouse button-1, or the touch-screen.Clicking mouse button-2 on a link causes its address to be displayed in the.I statusline of.IR charon 'sdisplay.Navigation to other information is achieved by clicking on the URL entryfield and typing the address of the resource, followed by the Enter key..PPThe retrieval and processing of the current pageis immediately terminated by clicking the Stop button..PPAs resources are browsed, a history of their web addresses (URLs) is built up.At any time you can navigate forwards and backwards through this list usingthe Forward and Back buttons.Additionally, clicking the History button, displays the entire history list as a set of.I linksenabling the user to quickly jump to any position in the list..PPSometimes, it is not possible to retrieve all of the components of a web document at the timethat it is requested.Often this is because the remote server is very busy or not available.This can result in the presentation of the document being incomplete or even corrupted.Clicking the Reload button causes.I charonto attempt to retrieve the current document and all of its components again..PP.I Charondisplays a progress panel to indicate the download status of each of the components of thecurrent document.The progress panel is displayed at the bottom of the.I charonwindow.Each component of the current document is represented by a rectangular block in theprogress panel.As the download of a component progresses, its corresponding block is gradually filled in.If an error occurs while downloading or processing the component, its block is coloured red.The component address and amount downloaded, or reason for failure, canbe obtained by clicking mouse button-1 on its progress block..SS "Web Standards"Standards are the life-blood of the World-Wide-Web;without them, the web could not exist.Web standards are under constant review with revised editions and complete new standardsbeing published all of the time.This section lists the standards supported by.I charonat the time of writing this manual entry.The version of the standard is given, if appropriate, alongside any comments on itsimplementation..PP.TP 15ProtocolsHTTP versions 1.0 and 1.1.IPHTTPS: SSL Protocol versions 2.0 and 3.0.X.509.v3 server certificates..IPFTP:.I charonsupports retrieval of plain text files only, directory listings are not generated..IPFILE:.I Charonattempts to determine the file type by a combination of the filename extension andexamination of the first few bytes of the file.  Directory listings are not generated..TPHTMLIt is intended that.I charonsupports HTML version 3.2, but in reality there isno single standard!.I Charonattempts to be as close as possible to Netscape Navigator Version 3 in terms of itsmarkup support.Obvious bugs in Navigator 3 andthe Netscape security model have not been adopted..TPJavaScript.I Charonimplements ECMAscript-262 2nd Edition, which is roughly equivalent to JavaScript1.1.The ECMA-262 standard does not define the.I hostobjects and classes that should implemented by the browser..I Charonimplements the set of host objects and classes of Netscape Navigator version 3..TPEncodingsUS_Ascii, ISO_8859_1, UTF_8, Unicode (big-endian).TPImagesGIF87a and GIF89a - animated GIFs always loop..brJPEG, XBitmap, Inferno BIT.IR image (6)format..SS ConfigurationWhile using.IR charon ,a sub-set of the configuration options can be modified.Clicking the Configuration button displays a config popup window, enabling the userto modify the current values of the available options..PPThe full set of configuration options can be modified on the command line or ina configuration file.Comand line options are processed after the configuration file.The configuration file is loaded from.BI /usr/ user /charon/configwhere.I useris obtained by reading the file.BR /dev/user .If this file does not exist, the file.B /services/config/charon.cfgis read instead.Options are processed in order; some options override settings affectedby others and so the order in which they are used is important..PPOptions are specified using a.IR key ,.I valuepair.On the command line this takes the form:.IP.BI - key.I value.PPWhere.BI - keyand.I valueare individual items in the argument list to.IR charon ..PPIn the config file options take the form:.IP.IB key = value.PPWhere.I valueis the remainder of the input line after the.BR ` = 'character.Any text lines in the config file that start with a.RB ` # 'character are ignored as comment lines..SH OPTIONS.TF 10.TP.B userdirThe directory where.I charonexpects to find its configuration files such as, bookmark and cookie files.The default value is.BI /usr/ user /charon/where.I useris obtained by reading the file.BR /dev/user ..TP.B starturlSpecifies the URL of the first document to be displayed by.I charonat startup.The default value is.B file://localhost/services/webget/start.html.TP.B homeurlSpecifies the URL of the document to retrieve when the Home button is clicked.The homeurl can only be changed if the.B change_homeurloption is enabled.Setting .B homeurlalso set the value of the.B starturloption.The default value is.B file://localhost/services/webget/start.html.TP.B change_homeurlEnables editing of the Home URL in the configuration popup window.A non-zero integer value enables this option, all other values disable itThis option also enables the.B homeurl option.The default value is 1..TP.B helpurlSpecifies the URL of the document to retrieve when the Help button is clicked.The default value is.B file://localhost/services/webget/help.html.TP.B httpproxySpecifies the host name and port of a web proxy server.The address is given in the form of a URL, where the optional port numbercan be specified after the server name by separating them by a colon.RB ` : '.The default value is the empty string, specifying that no web proxy server should be used..TP.BI noproxy " or " noproxydomsSpecifies a list of network domains for which a web proxy should not be used.The domains in the list can be separated by semicolon, comma, space or tab characters.The default value is the empty list..TP.B usesslExtends SSL support.Accepted values are.RB `` v2 ''and.RB `` v3 ''.Initially SSL support is configured off.Enabling version 1 or version 2 support restricts SSL support to that specific version.Specifying the option twice, once with each of the options, enables dual versionSSL support whereby the remote server is probed to determine which version it supports.Some servers only support one of the versions and may not tolerate the specialversion2/3 probe..TP.B buttonsSpecifies the set of buttons that appear on the window manager title-bar.The buttons are given as a list of button names separated by comma, space or tab characters.Valid button names are.BR help ,.B resizeand.BR hide .The default value is for all buttons to be displayed..TP.BI defaultwidth " or " widthSet the initial window width.This option is only meaningful when running under the window manager.If the specified width exceeds the screen width then the screen width is used.The default value is 630..TP.BI defaultheight " or " heightSet the initial height of the main display panel, this does not include the heightof the control and progress panels.This option is only meaningful when running under the window manager.If the total height of the.I charonwindow exceeds the screen height, the main display panel height will be reduced to fit.The default value is 450..TP.BI x " and/or " ySet the initial window position.These options are only meaningful when running under the window manager.The default value for both options is 0..TP.B imagelvlSpecify how to handle image components of a document.This option takes a numeric argument.A value of 0 prevents images from being downloaded or displayed.A value of 1 will download and display images but not animate GIFS - only the firstframe of an animated GIF will be displayed.A value of 2 or more enables full image processing.The default value enables full image processing..TP.B imagecachenumSpecify the maximum number of images that can remain resident in the image cache.The default value is 60..TP.B imagecachememSpecify the maximum amount of image memory available to the image cache in bytes.The cache is managed such that neither the.B imagecachenumnor.B imagecachememlimits are exceeded.The image cache tries to ensure that no more than 80% of available system image memoryis taken by the cache, irrespective of the value of this option.The default value is 80% of the system image memory that was available.I when charon was started..TP.B docookiesEnable cookie handling.A non-zero numeric value enables cookie handling, all other values disable it.The cookie cache is maintained in the.B cookiesfile in the.I userdirdirectory.The default value is 0, cookie handling disabled..TP.B doscriptsEnable JavaScript support.A non-zero numeric value enables JavaScript, all other values disable it.The default value is 0, JavaScript processing disabled..TP.B showprogressA non-zero numeric value results in the progress panel being displayed.All other values hide the progress panel, leaving more vertical space for the maindisplay area.The default value is 1, causing the progress panel to be displayed.TP.B httpSet the version of HTTP to use when communicating with web servers.Supported versions are 1.0 and 1.1.Any value other than 1.1 results in HTTP1.0 being used.The default value is 1.0..TP.B nthreadsSpecifies the maximum number of concurrent downloads of document components.Generally, if this number is higher, pages will complete faster as.I charonwill not have to wait for the download of one component to complete before anothercan be started.The downside is that a higher number of concurrent downloads will use more memoryduring the download process.The default value is 4..SH FILES.TF /services/config/charon.cfg.TP.B /services/config/charon.cfgThe default configuration file..TP.IB userdir /configThe.I userspecific configuration file..I userdiris given by the value of the.B userdiroption..TP.IB userdir /cookiesThe cookie cache..I userdiris given by the value of the.B userdiroption..TP.B /services/webget/start.htmlThe default start page..TP.B /services/webget/help.htmlThe default help page..SH SOURCE.TF /appl/lib/ecmascript/.TP.B /appl/charon/The main.I charonsource files..TP.B /appl/lib/ecmascript/Javascript (ECMA-262) implementation..SH BUGS.I Charonhas more than its fair share of real bugs.The following list documents the problems that are most likely to beencountered..PP.I Charonimplements its table layout as per the algorithm described in rfc1942.This sometimes results in table-based documents being laid out differently to otherbrowsers..PPJavaScript is a source of many problems.Many scripts do not specify the language version they employ.Additionally different language versions and browsers implya different set of.I hostobjects and classes.Such differences often give rise to syntax or null reference errors.This whole situation places a great burden on the script author to writesafe and compliant scripts; unfortunately authorsare rarely aware of this burden!.PPThe following elements of JavaScript1.1 are not fully implemented:.PP.BR Document.applets ,.B Document.embeds.I and.BR Document.plugins :Java Applets are not supported, the arrays are always empty..PP.BR Document.onunload :The property exists and can be assigned to, but the event is never raised..PP.BR Window.open() :A new window is never opened. If a URL is specified for the new window, thecurrent document will be replaced with that of the new URL..PPOther annoyances include:.PPWindow resize forces a complete document reload..PPFrames in a frameset are processed one at a time, not concurrently..PPIt is not possible to save downloaded data to file.  This is particularly annoyingfor MIME types that.I charondoes not support..PPThe history list can get confused, especially when following links in framesetsbefore the complete frameset has been downloaded.